Protective device



RE. OTTMAN.

PROTECTIVE DEVICE.

APPLICATION FILED 00129. 1920.

1,406,681,` Patented Feb. 14, 1922.

ffii/ew for UNITED STATES PATENT OFFICE.

ROBERT E. OTTMAN, OF EAST ORANGE, NEW JERSEY, ASSIGNOR TO WESTERN ELEC-TRIC COMPANY, INCORPORATED, 0F NEW YORK, N. Y., A CORPORATION OF NEWYORK.

PROTECTIVE DEVICE.

Specification of Letters Patent.l

Patented Feb. 14, 1922.

Application filed October 29, 1920. .Serial No. 420,464.

To all whom t may cof/wem Be it known that I, ROBERT E. OTTMAN, acitizen of the United States, residing at East Grange, in the county ofEssex and State of New Jersey, have invented certain new and usefulImprovements in Protective Devices, of which the following is a full7clear, concise, and exact description.

This invention relates to protective devices, and more particularly, toan improved method of assembling protector blocks used in open spacecut-outs.

A. type of protector block to which this invention is applicable,consists of a block of non-conductive material such as porcelain inwhich is secured a conducting electrode of carbon or similar conductingmaterial. The block of conducting materialis depressed a few thousandthsof an inch below the surface of the non-conducting block in order thatthe assembled unit may be placed in opposition to a second block ofconducting material and provide an Vopenl space air gap between adjacentconducting surfaces, without resorting to the use of a non-conductingseparator.

It isan object of the present invention to provide an improved methodfor assemling a conducting electrode in a block of non-conductingmaterial and depressing the surface of the electrode accurately apredetermined distance below the surface of the non-conducting block.

It is a further object of the invention to provide a method ofmanufacture which will permit assembling p`rotector blocks accuratelyand at a low cost.

To-attain these objects and in accordance with a feature of theinvention, a method of manufacture is provided in which the conductingelectrode is first placed in its approximate position and secured bysome cementing material such as a low melting point glass. It is nextheated to a temperature at which the cement becomes plastic or softenedand the assembled block is then placed in a jig provided with a diemember which permits the electrode member being accurately depressed thedistance required to give the specified separation required for theassembled cut-out. This and other features of the invention will be moreclearly understood by reference to the attached drawing in which Fig. lshows a protector 1 block in which an electrode is roughly seaccuratelypositioned; and Fig. 5 shows a completely assembled block lying adjacentto a plain carbon block to provide a complete cut-out as used inservice.

Referring now to these drawings, Fig. 1 is a cross-section view showinga block 7 of porcelain or similar insulating material in which issecured a carbon electrode- 8, this' electrode being held in place bymeans of a cement 9 consisting preferably of a low melting point glassas disclosed in a Patent No. 1,324,334 of December 9, 1919, to II.Boving. No attempt is made to place the electrode 8 accurately inposition and the surfaces of the carbon block are not ground.

In Fig. 2 there is shown a longitudinal section view of the block shownin Fig. 1, after the surface has been ground so that the surface of theelectrode 8 is in the same plane as the surface of the block 7. Theyblocks are'next heated so that the cementing material 9 becomesplastic. This is preferably done as shown in Fig. 3 by placing theblocks on a moving belt 11 which passes through an electric furnace 10,the speed of the belt and the heat of the furnace being such as toinsure the material 9 being plastic when the blocks emerge from theother side of the furnace. The block is next placed in a jig as shown inFig. 4, this jig being provided With a die member 12 having a projectingportion 13, which iswadapted to align ywith the electrode 8. By applyingpressure to the handle or lever 14, a block 14 operates to press theblock 7 against die 12, thus shown lying adjacent to a rectangularcarbon block 15 to form a complete protector unit as used in service.

Although itis preferable to grind the surfaces of the electrode and ofthe nonc'onducting block after theelectrode is secured within thenon-conducting block it is, of course, possible to surface the portionsseparately and then obtain the advantages of this invention in finallylocating thelectrode accurately in position.

What is claimed is:

l. A method of assembling a protector block which consists in cementinga conducting electrode in a non-conducting block, heating the blockuntil the cementing material becomes softened, accurately depressing theelectrode a predetermined distance and allowing the cementing materialto cool.

2. A method of assembling a protector block which consists in cementinga conducting electrode in a block of non-conducting material, grindingthe surface of said block and electrode until the surfaces lie in thesame plane, heating the block until the cementing material becomesplastic, depressing the electrode and allowing the cementing material toharden.

3. A method of assembling a protector block which consists in securing aconducting electrode in a block of non-conducting material by means of aloW melting point glass, grinding the surfaces of said block andelectrode until the surfaces lie in the same plane, heating theassembled block until the 10W melting point glass becomes plastic,placing the heated block in a jig, applying pressure to depress theelectrode the desired distance and allowing the low melting point glassto harden.

In Witness whereof, I hereuntoy subscribe my name this 22nd day ofOctoberA. D.

ROBERT E. OTTMAN.

